On a dry, windy cape in southern Antarctica, the ground is strewn with dead, mummified penguins. The rocks around them are littered with bones, pebbles and guano stains — the telltale marks of a freshly abandoned Adélie penguin colony.
Scenes like this are common around Antarctica's Ross Sea, which is home to millions of Adélies and other thriving penguin populations. Still, the sight at Cape Irizar puzzled biologist Steve Emslie, a professor at the University of North Carolina, Wilmington, when he visited in January 2016; he knew that Adélie penguins hadn't been spotted there in hundreds of years. Where had the remains of this ghostly colony suddenly materialized from?
Now, in a study published Sept. 18 in the journal Geology, Emslie offers an answer. A radiocarbon analysis of bones, eggshells and mummified skin samples collected at the site reveals that the seemingly fresh penguin remains at Cape Irizar are actually hundreds to thousands of years old. According to Emslie, the site has been occupied by breeding penguin colonies at least three times over the past 5,000 years, but the dessicated evidence of those occupations only just came to light, thanks to increasingly rapid snowmelt during Antarctica's ever-hotter summers.
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